public class test14_10_28 {
    /*给你单链表的头节点 head ，请你反转链表，并返回反转后的链表。



示例 1：

输入：head = [1,2,3,4,5]
输出：[5,4,3,2,1]
*/
    public static void main(String[] args) {

    }

    public class ListNode {
      int val;
      ListNode next;
      ListNode() {}
      ListNode(int val) { this.val = val; }
      ListNode(int val, ListNode next) { this.val = val; this.next = next; }
  }

    public static ListNode reverseList(ListNode head) {
        ListNode prev = null;
        ListNode curr = head;
        while (curr!=null){
            ListNode next = curr.next;
            curr.next = prev;
            prev = curr;
            curr = next;
        }
        return prev;
    }
}
